Flight indicators



Sept. 5, 1961 ca. J. CYPSER ET AL 2,999,237

FLIGHT INDICATORS Filed Feb. 29, 1960 2 Sheets-Sheet 1 26 COURSE ENE 11 INVENTORS F G 2 ausmv J. OYPSER I gon M0 R. DAYTON ATTSRNEY g manner by means of suitable circumferentially spaced roller discs (not shown) which cooperate with a circumferential slot in gear 19.

Compass card 16. is continuously stabilized withrespect to magnetic North. This is accomplished by means of a motor follow-up system mounted in the instrument and mechanically coupled to the compass card drive gear 19 through suitable shaft and gearing schematically illustrated in FIG. 3 by dashed line 25, the follow-up system being responsive to signals from a gyro stabilized magnetic compass, such as that shown and described in US. Patent 2,357,319. This motor follow-up system is schematically illustrated in FIG. 3 and constitutes a motor 20 energized from amplifier 21 whose input is an electrical signal proportional to the difference between the position of the compass card 16, as represented by synchro 22 mechanically connected to motor 20 through a gear train and coupling 25', and the magnetic heading of the craft, as represented by synchro 23, responsive to magnetic compass system 24. The compass heading of the craft is read preferably at the top of the instrument as defined by a fixed lubber line 26, FIG. 1. Also, since miniature aircraft reference 15 is also fixed, instantaneous aircraft heading may also be represented by a visual extension of the nose of the aircraft to the compass calibrations.

The circular opening 17 of the compass card defines a central area in the instrument face in which certain indicating elements of the instrument are viewed. The first of these elements is an elongated bar 30 that is mounted in the instrument for movement diametrically across the opening 17 and simultaneously rotates within the opening 17 about the center of the opening defined by the reference aircraft 15. As will become apparent as the description proceeds, the bar is diametrically displaced across the opening in accordance with the lateral departure of the aircraft with respect to a radiodefined flight path. The signal for operating the course bar 39 is provided from a conventional VOR receiver 38 on leads 39. A schematic disclosure of such a receiver is found in the above Reedy patent wlr'le a detaileddisclosure may be found in Technical Development Report No. 113, issued June 1950 by the CAA, entitled CAA VHF Omni-range. The course deviation bar 39 is simultaneously rotated about the center of the opening in accordance with the difference between the actual heading of the aircraft and the bearing of the selected radio beam. Thus, the bar 30 constitutes a heading stabilized course deviation indicator and provides the pilot with a plan picture of the azimuth attitude of the craft with respect to a radio track.

Referring to FIGS. 2 and 3, the support for bar 30 will now be described. Rotatably mounted in the instrument housing is a U-shaped gimbal member 31 which is mechanically supported by an elongated trunnion 32 extending between two of the walls 12 (only one of which has been illustrated in FIGS. 2 and ,3). The forward ends of gimbal 31 support a further circular mask 33 which forms a background member for the bar 30. Mounted between the arms of the gimbal 31 is a meter movement34 to which the bar 30 is attached by means of an elongated meter arm 35 extending through a suitable elongated opening or slot 36 in the mask 33. As shown schematically in FIG. 3, this meter movement is energized by the isignal'on lead 39 from receiver 38 which varies in accordance with the lateral deviation of the aircraft from a selected radio beam.

The mask 33 carries deviation dots which constitute a scale for indicating the magnitude of the deviation of the craft from the beam. Also, the mask 33 has a central portion 37 thereof which is raised and contoured to conform with the circular movement of the bar 30 about the meter movement pivot. This raised portion serves a dual function of reducing parallax between the bar 30 and the reference dots on the mask 33 and to provide flight director and/or autopilot.

4 an aperture through which the to-from flags (to be described) may be rendered visible.

The gimbal 31 is rotated in accordance with two inputs. These inputs are schematically illustrated in FIG. 3. One of the inputs is from the compass system 24 and the other is from a manually settable course selector knob 40. The input from the compass system is provided through gear 41 which meshes with a gear 42 at the rearward end of the gimbal 31. Gear 41 is driven through mechanical connection 42' from compass follow-up motor 20 through one input to a difierential 43. The input from selector knob 40 is by way of mechanical connection 44, through the other input of differential 43 to connection 42' and gear 41. Thus, the azimuthal position of the course deviation bar 30 about the miniature aircraft 15 may be manually adjusted to any desired magnetic heading and thereafter it will be rotated with the compass card as the aircraft changes its magnetic heading. In order to insure an accurate setting of the gimbal 31 and hence the bar 30 with respect to the compass card 16, a course marker 45 is provided. This marker is moved simultaneously with the gimbal 31 through ring gear 46 through mechanical connection 47. Ring gear 46 is mounted adjacent the compass card ring gear 19 and supported in the same manner as ring gear 19. A further and even more accurate indication of the course selected by rotation of knob 40 is provided by means of a drum-type counter located in the upper left-hand corner of the instrument face (FIG. 1) and driven by a direct mechanical connection 48 from the course set knob 40. The counter also insures an accurate setting of course when the desired course lies near the bottom of the instrument.

As clearly disclosed in the above-mentioned Reedy patcut, when the instrument of the present invention is used in flying a VCR radial, the course selector knob 40 simultaneously positions a course resolver 49 which serves simultaneously to set the VCR receiver 38 through leads 26 and 27 to provide left-right deviation information from a radio-defined radial corresponding to the set compass heading. Also, driven directly from mechanical connection 42 is a course error control transformer 50 for supplying to other instruments, such as flight director and/or autopilot, a signal corresponding to the course error, i.e., it constitutes a remote course selector for the The detailed operation of the azimuth stabilized course deviation indicator portion of the present instrument described herein-above is clearly set forth in the above-described Reedy patent and therefore will not be repeated here.

Very briefly, the operation is as follows. When flying a VCR navigation system, the pilot rotates the course selector knob 40 until marker .5 lies adjacent the magnetic heading corresponding to the magnetic heading of the desired VOR radial. In so doing. he positions the gimbal 31 and hence meter movement 34 and bar 30 to the same angular orientation. If the aircraft lies to the right of the radial so selected and is flying a path substantially parallel thereto, the appearance of the instrument will be that illustrated in FIG. 1. In order to cause the craft to approach and maintain the selected radial, the pilot turns to the left. As the aircraft changesv heading, both compass card 16 and bar 30 will rotate clockwise, the bar 33 still being displaced from the center of the instrument but now lying diagonally above and to the left of the miniature airplane 15. As the craft approaches the beam, the bar 30 will approach the center of the instrument. The approach is continued by the pilot now changing heading in a counter-clockwise direction which again simultaneously rotates gimbal 31 so as to bring the bar 30 in alignment with the fore and aft axis of the miniature airplane 15 as the deviation approaches zero. Proper control of the aircraft in accordance with the movement of the bar with respect to the miniature aircraft will result in an asymptotic approach to and maintenance of the selected VOR radial.

Qperation when flying a localizer beam of *anEILS is substantially identical. The-magnetic bearing of-the-localizer beam issimilarlysetin by the course knob 40.

Dueto the character of thewOR radio -system and its receiver on the'aircra ft, information is provided which informs the pilot whether '-'he is flying 'toward' "or away 'from theVORstation. Themanner imwhich this To- Froni-signal is generated-in the radio receiver 38 isdescribed in detail in the above-mentioned CAA report and need not be repeate'd here. It may simply be stated that when -a pilot selects a "VQR :radial, he simultaneously selects the radial-'displace'd w therefrom' which therefore provides a signal in one sense when i=the:aircraftis approaching this 90 radialsand' in ithe opposite sense when the-aircraft passestsuch radial. This reversing signal is converted ato a reversible polarity D.C. =voltage which appears on lead 60- in :3. iTheTo-Frominrdicationis-provided by two triangular-elements 6:1:and 1.62 (FIG. 1). "These "triangularrelements :or :arrowheadsare actuated by meter movementsi-l, 62',arespectivelyflwhich in turnaresecured shy-meansof suitablezbrackets to gimlaal 31 and hence rotate therewith :and are :connected with the arrowheads nL-ozhyrmeanskof Leshapedarms 63 and '64 (FIG. 1). 'll hemeterimovemcnts.aredocateii at the forward :end of the fgimbal .31candzthe -arms 63 and 64-extend into thesspacei65 :(EIGS.'2;and;3) lefthy -the curvedfout'portion;37 ofnnaskfifi. Thearrowheads 61 and '62 mounted {011 "these arms "are caused to move through the slots Lflfiflfid thy raised :mask portion :37 :to positionsin1bak rorsin front'thercof toitherebyhe rendered visible or invisible to the pilot. Also, suitablesstqps ;(:see FIG. :1) are tprovidedzforlimiting:thenrnovement of the arms 63 and -64 ;tothezpositions :illustrated when current through the meter movements tflow in one direction :or-fthemther. :Each:of :thezmeter movements ,61, 62'-are so spring zbiased :that when m fI-To-From signal ;-is :supplied, .both arrowheads twill 5-138 biased -.to their invisible rpositions. That :is, tthey "will both lie behind the raised portion 37ofmaskfi3. :IIlrFIG- 11, .thisis 'the'condition illustrate'd. As shown "schematically :in FIG. 3, ,-.meter movements i61',-62'-are connected in series with theiD.C. signal appearing on .lead .60. Thus, for example, if a positive :signal is .aPPIied :across the :meter movements, -one flag, say flags61,--.willrhecausedttorrotate to the position :shown'inidondash linesin FIG. .lwhile flag 62 will remain 'where :it :is, :its ;meter movement 1.62 tending to driveithe arm :64 :harder vagainstits@stop. The action is, of course, reversed when lthe To-From signal reverses polarity.

#In accordance with zazfeature'ofthe present invention, -the tarrowheads 61 and 62, together with- "their :meter movements 561'". and .62, are so relatively arranged on the gimbal :31 that when one A01 tthelotherrof the arrowheads is visible, ;it lies :closely adjacent the inner j periphery of -the zcircularzopening I17 in the .compass card .16. There- :-fore, when the aircraft is squarely on the .beam and the pointer 3.0 is lined 1UP directly .With thelminiature-airplane 315, the indicator element 61or562will form an arrowhead rfor the bar'30, and thence .an entire arrow having shaft :and ahead, pointingin the direction of the selected VOR sstation. :Since -thei-torfrom arrowheads lie .closely. adjacent .thesinner periphery entire-compass cardtopening 1'7, iitt is obviouslyhesirable that.there.be-.no indicating ele- -mcnt within .the opening which will, :under any .theading :condition obscureithe arrowheads.

It should :be ,pointed -.out .thaL-no -to-from information .is .provided during -.an. ,instrument approach .to. an airport 331152111113 system, andnoto-fromrsignal will'be applied ttorleadsm and v both-arrowheads 6,1 and 62 .will .be springtbiased topositions behind .the raisedportionf37 of mask .33. lrherefore, in VORtoperation, .theopening 17 should .-be.kept.-free;of .any indicating element which wouldin- -.,terfere with the .tofrom arrowheads, .as will become evident below. I

:AS flfl added .conveniencathe instrument is also provided with a heading selector knob 51 which, through mechanicalconnectionSSZ, difierential SS and-connection -54 FIG. -3;),-drives a heading selector index 55 -(FIGS. 1 and "2) "througha ring gear 56-to which-the iridexiis attached. 7 Ring gear 56 is mounted in 'the instrument in 'the sa me manner as-ringge'ar-s19and 4'6. :Heading seilector knob 51 rotates heading error control transmitter '57 which may be-usedas a remote heading selectoffora flight director and/ or autopilot. After having been --set to the-desired magnetic heading, marker '55 is thereafter driven=withthe compass card-l6rthrough:mechanical connection-58 from compass follow up motor 20.

As -a still further convenience, the instrument -may' be provided'with a niiles-to-dcstination counter operated tin accordance with the *DMEs'igna'ls, the counter beingflocated -in the upper rig'ht hand corner of the instrument "face (FIG. l).

The instrument of: the ypresent invention also includes indicator means *for aidingthe pilot in approaching-rand maintaining the glide slope beamof an 11.5. Referring to FIG. 1, this indication is provided by a second bar 70 which -isrmountedin the instrument to move -diametricallfacross opening 17 in the instrument' face.

However, the j-bar always remains horizontal and may 'be suitably colored "or marked to distinguish'it'from the course deviation bar'30. Glide slope bar is actuated by means-of ameter movement 71 fixedly-mounted in the instrument housing, *as by'means of'brackets "72, on one of ithewalls F12 and is-coupled with bar '70"by-means an-elongated connecting-member. Of course, the bar "7 0 and" member 73 may 'bc made in one piece asshownin -FIG. 3. The glide slope *bar 70-isnormally springcentered, that is, the meter movementa'spring causes the' bar 7.0 to lie :infits =zero position when there is no 'energizationnf meter-mot ement. "This zero position vissuchitha't the*bar'70liescentered inthe "opening 17, Le -directly under the ;wings of miniature airplane 15. Meter movement 71 'is "energized from the "output-of --a glide :slope receiver "75 .iof conventional construction through lead '76'as schematically illustrated '-in FIG. "3. I

.It will be'noted'that-there areno displacement dots" Onthe'mask 33 against which'the glide slope bar 70 may be read. "Ihe; reas0n-'for this is that the instrument iis' used morefor enroute navigation-and initial ILS sapproach .than' it is during let-down on final approach. However, it-is. still desirable to provide some form :of scale under the 'latter "conditions against which the glide vslope 'barmay ,be ,read so that:the pilot will have :some .ideaof the absolute magnitude *of his displacement-from ,glide slope'beam. The instrument of the present invention provides. ascale 7 7;,for this purpose. In accordance with the tobiects of the present "invention,;-this scale is moved out of the way under allflight conditions other .than theffinalglide slope approachthereby renderingtthe central opening11'7 of the instrument uncluttered'with unnecessary indicating elements "and insuring that the arrowheads .161 or "62 will always be'visible during VOR operation no ;,matter whattheheading of'the craft may .be.

.To furtheriremove the .opening 117 when they .are not being used, means have been provided for moving .the glide 'slope barf-#0 irom viewdu'ringVOR operation. This means is-shown schematically ,infFIG. '3. Frequency selector knob ""18 of receiver .38 controls a switch '7 9 which in turn v.trols the energization of.relay80,"energizationofwvhieh vcontrols suitable switching 8,110 supply glide slope fbar meter movement 71 "with abias potential which in $111171 -moves the glide slope bar 70 upwardly and behindthe compasscard 16 which, in ,thiscas e, obviously serves as a mask for ohscuring'the gli'de slope bar. This *bias is supplied from a :suitable source 'of 5D .C. voltage' 82.

Thus,whenever theirequency selector-knobflfi is rotated "for aVQRfrequency; switch 79 -is closed thereby supply- 'ing FDiC. woltage *to'relay 80 *and simultaneously, aupoh actuation of the-rlayg' to me'ter movement 4 'finirthe unnecessary indicating elements from I flag signal from the receiver.

other hand, whenever selector knob 78 is tuned to an ILS frequency, switch 79 is opened, relay 80 de-energized, and the meter movement 71 is connectedto the output of glide slope receiver 75. j 7

Glide slope scale 77 comprises a substantially flat member 85 suitably secured to the arm 86 of an actuating meter movement 87. Meter movement 87 is suitably fixedly mounted in the housing, as on one of the walls 12. The meter movement is energized by the glide slope receiver warning flag signal appearing on lead 88. This flag signal is a conventional output of a standard'glide slope receiver, such output serving to indicate when suflicient signal strength is being received for the pilot to rely on movements of the glide slope deviation indicator.

Glide slope reference means or scale 77 is provided with a straight edge 89 and is mounted in the instrument housing such that this straight edge is vertically disposed in the opening 17 and is therefore parallel with movement of the glide slope bar 70 upwardly and down- .wardly across said opening. Futhermore, when in its actuated position as shown in FIG. 1, this straight edge lies closely adjacent glide slope bar 70. The reference means 77 is provided with suitable graduations 90 for indicating to the pilot the magnitude of the craft displacement of the glide slope beam.

Fixedly mounted in the instrument directly behind the reference scale 77 when in its actuated position is flag element 91 which may be of a bright color and which may be provided with suitable letters, such as GS. Thus, when the scale 77 is not visible, warning flag 91 is visible thereby indicating to the pilot that he is not receiving proper glide slope signals.

The operation of the instrument when using a glide slope beam may best be described by considering an aircraft which is substantially on the localizer beam but which has not as yet entered the glide slope beam. Under this condition, the glide slope receiver is functioning (since it is turned on through suitable interlocking switch connection 92 associated with the ILS frequency selector switch 78), but no usable signal is being received. Therefore, there is no output on lead 76 and the glide slope pointer 70 lies in its centered or. zero position. Likewise, there is no flag signal on lead 88and the glide slope scale 77' lies behind the compass card 16. As the aircraft approaches the glide slope beam {usually from the underside), a fly-up glide slope signal will begin to be received and supplied to the meter movement 71. This signal may cause glide slope bar 70 to move slightly from its center position. However, the signal is still not strong enough to be relied upon and there is therefore no The glide slope reference scale 77 will remain behind the compass card 16, leaving glide slope warning flag 91 exposed and thereby telling the pilot to ignore any movement of the glide slope pointer 70. As the aircraft moves into the glide slope beam, and the received signal becomes stronger and stronger, the bar 70 will continue to rise and the reference scale 77 will gradually move to the right and finally cover warning flag 91 indicating to the pilot that he may now rely on the glide slope bar deviationand make whatever corrections in his flight path he deems necessary.

While the invention has been described-in itspreferred embodiment, it is to be understood that the words which have been used are words of description rather than limitation and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of the invention in its broader aspects; l

What is claimed is:

1. In an aircraft navigation indicator for. indicating to the pilot the position of the craft with respect to a radio-defined flight .path and including radio receiver means for supplying an outputin accordance-with the departure of said craft with respect to said flight path, pointer means displaceable across the face of said indicator in accordance with departures of said aircraft from said flight path, reference means mounted in said instrument for movement from one position in said instrument invisible to the pilot to another position therein visible to the pilot and adjacent said pointer whereby when in said other position to provide a visible reference for said pointer, and means responsive to the magnitude of the output of said receiver for moving said reference means from one position to the other.

2. The apparatus as set forth in claim 1 further including warning means so positioned in said instrument face that it will be rendered visible when the scale is in said invisible position.

3. In an aircraft navigation indicator for indicating to the pilot the position of the aircraft with respect to a radio-defined flight path and including a radio receiver means for supplying an output in accordance with the departure of said craft with respect to said flight path, said instrument having a window therein through which indicating elements of said indicator may be viewed, a mask within said window for defining an opening in said window, pointer means displaceable across said opening in accordance with departures of said aircraft from said flight path, reference means mounted in said instrument for movement from one position behind said mask to another position within said opening and adjacent said pointer whereby when in the said other position to provide a reference for said pointer, and means responsive to the magnitude of the output of said receiver for moving said reference means from said one position to the other.

4. In an aircraft navigation indicator for indicating to the pilot the position of the craft with respect to a radiodefined flight path and including radio receiver means for supplying an output in accordance with the displacement of said craft with respect to said flight path, said instrument having a circular viewing opening, a pointer ele ment positionable in said instrument face for movement diametrically across said circular opening, a member having a straight edge and a reference scale along said straight edge, said member being supported in said instrument such that said straight edge is parallel to the direction of movement of said pointer, means for moving said scale member from a position external of the periphery of said opening to a position within the periphery of said radio receiver means is rendered effective, reference scale for said pointer, and means responsive to the mag nitude of the output of said radio receiver for moving said scale from one position to the other.

5. In an aircraft navigation indicator for indicating to the pilot the position of the craft with respect to a radiodefined flight path and including radio receiver means for supplying an output in accordance with the departure of said craft with respect to said flight path, pointer means displaceable across the face of said indicator in accordance with said output, means for rendering said pointer means invisible to said pilot when said radio receiver means is rendered nonefiective, means for moving said pointer means to a position visible to said pilot when said radio receiver means is rendered effective, reference means mounted in said instrument for movement from one position in said instrument invisible to the pilot to another position therein visible to the pilot and adjacent said pointer whereby when in said other position to provide a reference for said pointer, and means responsive to the magnitude of the output of said receiverlfor moving said reference means from one position to the other.

6. A radio navigation indicator for aircraft having first and second radio receiver means for suplying first and second outputs respectively proportional todeviations of said craft from radio beams defining a' flight path, comprising an instrument housing having a window therein and a mask within said window having a substantially circular opening through which the indicating elements of said indicator may be viewed, a first indicating element positionable in said opening for movement diametrically thereacross in accordance with said first output, a second indicating element positionable in said opening for movement diametrically across said opening in accordance with said second output, means for rendering said second element invisible to said pilot when said second radio means is rendered non-effective, means for moving said second element to a position visible to said pilot when said second radio means is rendered eflective, a member having a straight edge and a reference scale delineated along said straight edge, said member being supported in said instrument such that said straight edge is parallel to the direction of movement of said second element, means for moving said scale member from a position behind said mask to another position within said opening and adjacent said second element whereby to provide a straight edge reference scale therefor, and means responsive to the magnitude of the output of said second radio means for moving said scale from one position to the other.

7. In an aircraft navigation indicating instrument for indicating to the pilot the position of the craft with respect to first and second radio transmitters which define azimuth and elevation flight paths respectively for said aircraft and including first and second radio receiver means, said first receiver supplying a first output in accordance with lateral deviations of said craft with respect to said azimuth flight path and a second output in accordance with the direction of the position of said craft with respect to said first transmitter parallel to said azimuth flight path and said second receiver supplying an output in accordance with vertical deviations of said craft with respect to said flight path, the combination comprising an indicator housing having a substantially circular viewing opening therein, means defining at least a part of a diametral line across said opening, a first elongated bar supported in said instrument with its length parallel to said diametral line and laterally displaceable relative thereto in accordance with said first output, means for rotating said line in said opening in accordance with the difference between the heading of said craft and the bearing of said azimuth flight path, arrowhead defining means and means for mounting said arrowhead defining means in said instrument for movement from a position invisible to the pilot to a visible position. adjacent the periphery of said opening and at one end or the other of said diametral line whereby when said craft is on said azimuth flight path said bar and arrowhead form an arrow pointing in one direction or the other with respect to said first transmitter, means for actuating said arrowhead defining means in accordance with said second output, a second bar displaceable diametrically across said opening in accordance with the output of said second receiver, reference means for said bar having a straight edge and a reference scale therealong, means for mowably supporting said member in said instrument such that said straight edge is parallel to the direction of movement of said pointer, actuating means for said member for moving said member from a position within the periphery of said circular opening to an invisible position external of the periphery of said opening when said magnitude drops below a predeterminedtvalue whereby said scale does not obscure said pointer arrowhead when said second radio receiver cannot be used.

8. In an aircraft flight indicating instrument having a Window therein, a mask in said window defining 'a circular opening through which indicating elements of the instrument may be viewed, an indicating element mount ed in said instrument for movement across said circular opening, a reference member for said element having a straight edge, means for supporting said member in said instrument such that said straight edge is parallel to the direction of movement or said element, and means for moving said member from a position external of the periphery of said opening to a position within the periphery of said opening whereby said member provides a straight edge reference for said element in said circular opening when in said latter position.

No references cited. 

